1. Field of the Invention
This invention relates to an ozone-decomposing catalyst for efficiently decomposing ozone.
2. Description of the Prior Art
In electrophotographic duplicating machines generally employed, it is a common practice to uniformly charge one surface of a photoconductive electrically insulating layer formed on an electrically conductive support using a system wherein a high voltage is applied between fine lead wires to cause a corona discharge therebetween and the photoconductive electrically insulating layer is passed into the charging zone to impart an electric charge to the layer. In an electrophotographic duplicating machine using a charging system of the type just mentioned, the corona discharge takes place in the air, so that ozone is readily produced by reaction of oxygen molecules in the air with both the charged particles accelerated by the discharge field and the activated particles of oxygen produced as a result of the non-elastic collision of oxygen molecules. The air containing the thus produced ozone is forcibly exhausted from the duplicating machine by means of an exhaust device provided within the machine.
Ozone has a strong oxidizing action, and numerous uses have been therefore proposed in sterilization of air which may contain germs suspended therein, deodorization of air, etc. Ozone generally gives off an intensely strong odor and may cause physiologically adverse effects such as shortness of breath, dizziness, headache, nausea, etc., even if ozone is present in the air at a concentration as small as about 0.1 ppm. Accordingly, it cannot be said positively that ozone is harmless to the human body. Thus, a duplicating machine using a corona discharge as an office machine has a disadvantage due to the generation of ozone.
In order to remove the ozone discharged from an electrophotographic duplicating machine, a number of methods have been proposed, e.g., a method, as disclosed in U.S. Pat. No. 2,203,188, for decomposing ozone into innoxious oxygen by passing the ozone-containing air in an exhaustion step through an ozone decomposing catalyst-packed bed, or an ozone decomposing catalyst-deposited on a non-woven fabric or filter layer, a method, as disclosed in U.S. Pat. No. 2,980,494, for decomposing ozone wherein an ozone decomposing catalyst is fixedly deposited on the surfaces of blades of an exhaust fan or blower of an exhaust device provided within the electrophotographic duplicating machine to permit the ozone-containing air to be efficiently brought into contact with the catalyst due to the high velocity revolution of the blades, a method, as disclosed in U.S. Pat. No. 2,298,607, for decomposing ozone wherein an ozone decomposing catalyst is fixedly deposited on the surfaces of a shield case of a discharging device to allow the ozone to be decomposed immediately after generation, etc. Known ozone decomposing catalysts used in these methods include manganese dioxide; lead peroxide; other metal oxides such as chromium, cobalt, copper, nickel, and a mixture thereof; metals such as nickel, rhodium, etc. However, these ozone decomposing catalysts all have a low ozone decomposing efficiency and a short life. There is accordingly a strong demand for an ozone decomposing catalyst which overcomes the above disadvantages.